Add install docs

[zenmonkeykstop]

Adds installation docs page in Admin section.

[eloquence]

First pass visual review.

[rocodes]

LGTM - few changes as a result of our walkthrough

[emkll]

docs look great @zenmonkeykstop , left a few comments inline

[emkll]

is freedomofpress/securedrop-workstation#505 worth noting?

[eloquence]

IMO if we expect that warnings will be shown then we should note it here.

[zenmonkeykstop]

This is a bug that we should fix. We should not expect users to interpret error messages to figure out if they're "okay" ones.

[eloquence]

Regarding the recommendation for the default user password:

• Any user with FDE passphrase can boot into single user mode, so this password provides limited protection against system compromise.
• It does provide some weak protection in the case where the laptop is left unattended, or against naive compromise attempts.
• User will have to type this password every time they log in and will never be able to copy/paste it, so a password like @LK$#\x<L:#$ seems highly undesirable.

With these tradeoffs in mind, I think we should use language like this:

We recommend setting a strong password or passphrase that you are comfortable typing repeatedly.

Qubes itself provides a strength indicator while you set the password, so I think this is sufficient guidance. Thoughts?

[eloquence]

Screenshots for the attach flow:

[emkll]

Provided the finding/changes in freedomofpress/securedrop-workstation#510 are valid, we should make an update to these docs as well.

[eloquence]

Added some notes to BIOS section; thanks a lot for putting this together and for your patience w/ review, these docs are really looking great already.

[eloquence]

Couple small comments re: the BIOS docs, and would still recommend copy/paste instructions for the steps performed in the work VM, but otherwise this LGTM from my end :)

[zenmonkeykstop]

Thanks, pushed a rebased version to keep the commit count down :)

[eloquence]

Looks great, doing a quick final visual review before merging. :)

[eloquence]

LGTM, thanks for all your hard work on this.